Switching colors of a texture painted texture
When texture painting, you can change the active colour in the brush settings which can be found in the toolbar region by pressing T.



You have two colours available under the colour wheel, press X to toggle between the two while painting.

While it hasn't been added to the manual, you can create palettes of colours to easily switch between common colours. You can find some info about using palettes at the bottom of these release notes.

After you have finished painting one of your colour versions, go to the UV/Image editor and save a copy of the texture image with a unique name so you have each version available later.